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ksym_tracer: Rewrite ksym_trace_filter_read()

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Reading ksym_trace_filter gave me some arbitrary characters,
when it should show nothing. It's because buf is not initialized
when there's no filter.

Also reduce stack usage by about 512 bytes.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A52E2B4.6030706@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Li Zefan 2009-07-07 13:52:52 +08:00 committed by Ingo Molnar
parent db59504d89
commit be9742e6cb
1 changed files with 18 additions and 11 deletions
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29
kernel/trace/trace_ksym.c
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@ -35,7 +35,6 @@
#define KSYM_TRACER_MAX HBP_NUM
#define KSYM_TRACER_OP_LEN 3 /* rw- */
#define KSYM_FILTER_ENTRY_LEN (KSYM_NAME_LEN + KSYM_TRACER_OP_LEN + 1)
struct trace_ksym {
struct hw_breakpoint *ksym_hbp;
@ -230,25 +229,33 @@ static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf,
{
struct trace_ksym *entry;
struct hlist_node *node;
char buf[KSYM_FILTER_ENTRY_LEN * KSYM_TRACER_MAX];
ssize_t ret, cnt = 0;
struct trace_seq *s;
ssize_t cnt = 0;
int ret;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
trace_seq_init(s);
mutex_lock(&ksym_tracer_mutex);
hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {
cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt, "%s:",
entry->ksym_hbp->info.name);
ret = trace_seq_printf(s, "%s:", entry->ksym_hbp->info.name);
if (entry->ksym_hbp->info.type == HW_BREAKPOINT_WRITE)
cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt,
"-w-\n");
ret = trace_seq_puts(s, "-w-\n");
else if (entry->ksym_hbp->info.type == HW_BREAKPOINT_RW)
cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt,
"rw-\n");
ret = trace_seq_puts(s, "rw-\n");
WARN_ON_ONCE(!ret);
}
ret = simple_read_from_buffer(ubuf, count, ppos, buf, strlen(buf));
cnt = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
mutex_unlock(&ksym_tracer_mutex);
return ret;
kfree(s);
return cnt;
}
static ssize_t ksym_trace_filter_write(struct file *file,